Electric-current rectifier



July 31; E28. 1,678,824

S. RUBEN ELECTRIC CURRENT RECTIFIER Filed April 16, 1925 avweutoz571M051. RUBEN v 20 be obvious and v 30 filed arch 5, 1925.

Patented. July 31, 192a.

UNITED STATES RAT NroF-FlcE.

sum, or new Yoiax, N. Y., Assrenon iro :auu'mw' ame coarom non ornamwm's mosaic-comm:

muses fled A ril 1a, 1925. swarm. 23,582;

This invention relates to electric current rectifiersand the like, andparticularl to the dry surfacefcontact variety, m w 1ch electrodeelements relatively divergent 1n the 5 electro-chemical series aredisposed 1n mt1- mate contact to give a rectifying efi ect.

' The object generall of the mventlon is to provide an improveconstruction for devices of this character whlch is eflicient,economical and readilymanufactured;

' More specifically, an object of the mvention is to provide anarrangement vof the electrode elements in the elemental rectify ing orasymmetric couple whichprovides for a relatively'high-degree ofintlma-te contact between the electropositive and the electronegativeelements, particularly when thelatter is in pulverulent form. I 0

Other objects of the inventlon will 1n part will'in part appearhereinafter. I

The invention accordingly comprlses the features of construction,COmbillfitlOILOf elements and arrangement of parts which will 26 beexemplified in the COIlStIIlUtlOIl' herelnafter set forthand the scopeof the apphcai tion of which will be indicated in the clalms.

This application is a continuation 1n part of In prior applicationSerial No. 13,143,

For a fuller understanding of the nature and objects of, the inventionreference should a be had to the follow' detailed descrlpt on taken inconnection with the accompanymg :6 drawing, in which: p j

The fi re shows, malnly diagrammatical- 4 1y, an elemental asymmetriccouple arranged in accordance with the invention and adaptfying andbattery-charging served for recti 40 ice. I I

In the practice of the present IIIVGIltlOD- the electropositive elementcomprises a metal of the antimony grou in close surface contact with apulveru ent dry film-forming electro-ne ative materialppreferablyasinetallic oxi e. To obtain the most eflicient current rectificationthesurface of the metal. electrode should be oxidized before the assemblyof thlenelements-of the cou 1e I I lb The prefe (1 method for pro uclngthis oxidized surface is by connecting the electrode as theanode in adirect current circuit at about 150 volts, and in"discharging a cur-"rent thereto when immersed in asaturated solution of a film-fornriingsolution, such as 6 connected as the'anode in an alternatin isfactory.

' eflicient of these ammonium borate. This preformed oxide coatingcoacts to maintain readily the inverse current blocking filmwhich'obtains at the contacting surface when the electrode is currentcircuit, but ermits the flow of cl fi're'nt to theadjacent e ectrodewhen connected as thecathode, thereby effecting the rectification of thealternatm current.

As the electropositlve electrode element, various film-forming metalsmay be used; for example, antimony maybe-used or o e of the kindredmetals in the fifth group, 0 the periodic table of chemical elementswhich have relatively high atomic weights. The metals bismuth, tantalum,antimony and niobium have been found to be satisfactory; metals of lessatomic weight than niobium have notbeen found to be practical. Of themetals enumerated, tantalum is the most sat-' "As the electronegativeelectrode element which is adapted to react to form the oxide film,metallic oxides are employed which serve as an oxide reserve in case theoxide '8 lilm breaks down. Such metallic oxides may be, for example, theoxides of manganese, the iron oxides, vanadium oxides, and leadperoxide. When tantalum is used, the most metallic oxides is leadperox1de. a

Relatively. satisfactory results are obtained by applying'the'I'netallic oxides in powdered form mixed with a chemically inert bindersolution, as. a thin coating upon the electrode surface, andheating themix onductive components of ture until the non-c v the binder are burnedout, and the particles of the metallic oxide coalesce over'the electrodesurface.' Another method is to hold'in close surface contact withtheelectrode surface the metallic oxide'in powdered form. Referring now'to thedrawing, an electric circuit is shown, having therein 'atransformer T,storage'bat tery B andan. asymmetricor-current rectifyingcouple in which 1 denotes an oxide coated tantalum electrode stripextending within metal walled containe'r 3, and held in position byinsulating plugs4 and 4..., and'in surface contact with a film-formingelectronegative powder, lead peroxide, 2. The lead wires. are indirectcontact with tantalumelectrode 1, and the metal wall of container 3.

. Inoperation, as alternating current is apll! to produce a sufficientdrop of potential. It

plied, current passes to battery B when the tantalum electrode is thecathode, but is blocked and prevented from discharging through thecouple by the contact drop of potential between the surfaces of theelectropositive tantalum and the cooperating material electronegative toit, when the tantalum is the anode, in this way effecting currentrectification.

The formation of the film is of fundamental importance in all drysurface contacting rectifying couples. It has been found that allrectifying couples operating through the contact of an electropositivematerial with a material electrone 'ative with respect to it, functionentirely y a contact drop of potential at that surface. No currentrectification effect is obtained if, at the contacting surfaces of thosematerials the specific resistance is such as not been found that thetantalum-lead peroxide couple functions when the applied tentials'arelow, without the production immediately of a tantalum oxide film, but,due to the low specific resistance of lead peroxide, the-re is an excessinverse current discharge at higher potentials. This is reduced by thefilm of tantalum oxide resulting from the reactionbetween the tantalumand the lead peroxide, the "film then assisting in the operation of thecouple solely by its increased resistance, which is higher than has ithat of lead peroxide.

to be disposed in intimate contact with said Should the tantalum oxidefilm be punc tured or otherwise injured, the reaction be- ,tween thetantalum and the lead peroxide restores it to normal.

Having described my invention, what I claim as new and desire to secureby Letters Patent is: I 1. In dry surface contact rectifying devices andthe like, an asymmetric couple comprising an electro-positive electrodeelement formed of a-metallic body of the fifth periodic group having arelatively high atomic weight, and an electro-negative electrode elementformedv of a metallic oxide arranged to coperate in the production of aninverse current blocking film and adapted electro-positive electrodeelement.

2. In dry surface contact rectifying devices and the like, an asymmetriccouple comprising an electro-positive electrode element formed of ametallic body of the fifth periodic group having a relatively highatomic weight, and an electro-negative electrode element formed of leadperoxide arto cooperate in the production of an ranged current blockingfilm and adapted inverse,

. comprising an .least as great as to be disposed in intimate contactwith said electro-positive electrode element.

3. In dry surface contact rectifying devices and the like, an asymmetriccouple comprising an electro-positive electrode element formed ofmetallic tantalum and an electro-negative electrode element formed oflead peroxide, said electro-negative electrode being in pulverulent formarranged to cooperate in the production of an inverse current blockingfilm and disposed in intimate contact with said electro-p'ositiveelectrode element.

4.'In dry. surface contact rectifying devices and the like, anasymmetric couple comprising an electro-positive electrode elementformed of a metallic body of the fifth periodic grolup having arelatively high atomic weight and having a film coating of an oxidethereof, and an electro-negative electrode element formed of a metallicoxide, said clectro-negative electrode element serving as an oxidereserve and being in pul-v verulent form and disposed in intimatecontact with said electro-positive element.

5. In dry surface contact rectifying devices and the like, an asymmetriccouple comprising an electroositive electrode element formed of metallictantalum and having a film an electro-negative electrode element formedof a metallic oxide, said. electro-negative coating of an oxide thereof,and

and disposed in intimate contact with said electro-positive electrodeelement.

6. In dry surface contact rectifying de- Vices and the like, anasymmetric couple electropositlve electrode element formed of, ametallic body of the fifth periodic group having an atomic weight atniobium and having a film coating of oxide, and an electronegatlveelectrode element formed of lead peroxide, said electronegativeelectrode elementbeing in a pulverulent form and disposed in intimatecontact with said electropositive electrode element.

7. In dry surface contact rectifying devvices and the like, anasymmetric couple comprising an electropositive electrode element formedof metallic tantalum and having a film coating of an oxide thereof, and

an electronegative electrode element formed of lead peroxide, saidelectronegative electrode element being in pulverulent form and disposedin intimate contact with saidrelectro ositive electrode element.

. n testimon whereof, Sam Rmxmr has signed his-name to thisspecification, this fourteenth day ofApril, 1925.

' SAMUE L RUBEN.

